Utility lines, such as lines for telephones, electricity distribution, natural gas, cable television, fiber optics, Internet, traffic lights, street lights, storm drains, water mains, and wastewater pipes, are often located underground. Utility lines are referred to as “buried assets” herein. Consequently, before excavation occurs in an area, especially an urban area, an excavator is typically required to clear excavation activities with the proper authorities. The clearance procedure usually includes contacting a central authority that in turn notifies the appropriate utility companies. Subsequently, each utility company must perform a buried asset detection procedure, which includes visiting the excavation site, detecting the relevant buried assets and physically marking the position orientation of the buried asset using temporary paint or flags. Upon completion of this procedure by the appropriate utility companies, excavation can occur with the security that buried assets will not be damaged.
Conventional locators (commonly known as “pipe or cable locator receivers”) are portable, self-contained electronic devices carried by a field operator who walks over the target pipe or cable and receives an electromagnetic or acoustic signal from the buried conductor. A transmitter in the locator applies a signal to the buried asset. The locator includes detection antenna arrays, signal processing hardware and software, a display screen and power supply management circuits. The locator's display screen displays position, orientation and depth information of the buried asset to the operator.
Some prior art locators comprise portable upright or vertical profiles that use a receiver with at least two vertically separated antennas or sensors. This type of locator requires the operator to manually move the device across the above surface target area, searching for electromagnetic fields radiating from the underground conductor or buried asset. The operator then manually narrows the search area by moving the locator device through space so it is eventually positioned directly above the underground asset. Typically a peak or null response is presented to operator in visual or audible form. The vertical positioning of the sensors permit a depth calculation from the device to the target conductor. Once the target has been located, the operator can mark the position of the buried asset with a flag or paint marking device. Similarly, some prior art locators comprise portable horizontal bar profiles containing multiple separated antennas or sensors on a horizontal axis. As opposed to locators having vertically separated antennas or sensors, the horizontal type of locator is placed in a fixed stationary position above surface in an area believed to contain the buried asset. The horizontal bar type locator analyzes the signals directly under the device and remains in a static position while doing so. Complex vector algorithms predict the position of the buried asset relative to the horizontal bar's position and the user is presented with this data on a visual display. If no target is detected the operator is advised to reposition the device.
Both of these prior art devices have their advantages and disadvantages (speed, accuracy, operator skill requirements, cost, type of target conductor) and a variety of problems can result if both are not used to locate and accurately find the depth and position of a buried asset. Often two separate locaters—one horizontally oriented and one vertically oriented—are needed. Carrying around, maintaining and handling two, separate locator devices can be cumbersome and physically exhausting for a locate technician. Further, requiring two separate locator devices increases the complexity of the locating process, increases the associated costs (i.e., two locators must be purchased), and reduces reliability, since the malfunction of either locator leads to time lost. Further, it can be cost prohibitive for organizations that require large numbers of locators for their workforce to purchase the number of locators they require.
Therefore, a need exists for improvements over the prior art, and more particularly for methods and systems that increase the usability, reduce the complexity, and lower the costs of devices and systems that detect buried assets.